1. Field of the Invention
The present invention relates to a modular jack connector, and particularly to a modular jack connector optimized for 1000Base-T transmission and operating in a Category 5 cable environment.
2. Description of Related Art
Modular jack connectors have been used for more than 30 years in communications industry, originally to connect telephones to telephone lines. As technology has advanced, modular jack connectors have been adapted to keep pace with emerging needs. However, modular jack connectors are for use with copper wire cabling networks, which are rapidly becoming obsolete.
In communication networks today, the bulk of communication lines are still copper wire cables. This is particularly true in older buildings. The trend in communication technology is toward the use of fiber optic cables, which provide greater bandwidth and other benefits. Conversion of present copper wire communication networks to fiber optic networks promises to be very expensive, as it will require replacing copper wire cabling in buildings with fiber optic cabling.
Communication cabling networks are classified into different categories according to different performances delivered. Most copper wire cabling networks presently in use, together with their connectors, fall into Category 5, which have already replaced Category 3 systems. Category 5 has much more demanding requirements and delivers far greater performance. One benchmark for Category 5 performance is that NEXT (near end cross talk) be lower than xe2x88x9240 dB at 100 MHz (megahertz). Category 5E, or Enhanced Category 5, was developed after Category 5 to provide stricter control over the Category 5 electrical environment. However, the bandwidth is still 100 MHz. Category 6, which is as yet undefined formally by the EIA (Electronic Industries Association), is more demanding, and has been promoted in a few European countries where the expense and precision are deemed justifiable.
As demands on networks using four pair UTP (unshielded twisted-pair) wiring systems, such as transmission rates, have increased, development of industry standards has been forced to higher system performance. The Category 5 level performance defines electrical parameters for proper data signal systems that require up to 100 MHz frequency bandwidth, i.e., fast Ethernet 100Base-T. The latest data rates have increased up to 250 Mbps (mega-bits per second), i.e., 1000Base-T Ethernet, which allow LAN (local area network) systems to transfer data 10 times faster than 100BaseT Ethernet on UTP media cabling.
As applications become more bandwidth hungry, users are approaching a point at which outdated copper wiring will have to be replaced by fiber optics, which will be a great expense, especially in old buildings. If connectors can be devised to use presently existing wires in these old buildings to deliver Category 5 performance in 1000Base-T networks, the urgency for homes and businesses to make expensive change from copper wire cabling to fiber optics may be lessened, saving users a great deal of money.
However, presently available Category 5 arrangements yield a margined modular jack connector that fails to achieve satisfactory performance when utilized under the 1000Base-T Ethernet, or Gigabit Ethernet protocol, in despite of Category 5 connectors being called out in the specification. Present network installations generally use Category 5 UTP wiring and hardware that support the 100Base-T standard with two pairs of Category 5 UTP or STP (shielded twisted-pair) wire. In the 100Base-T scheme, one twisted pair (the {circle around (1)}-{circle around (2)} pair) is used for signal transmission, a second pair (the {circle around (3)}-{circle around (6)} pair) is used for signal reception, and the remaining two pairs (the {circle around (4)}-{circle around (5)} and {circle around (7)}-{circle around (8)} pairs) are unused. Correspondingly, as illustrated in FIG. 11, the modular jack connector for use with Category 5 copper wire cabling networks supporting the 100Base-T standard has 8 contacts arranged in the same manner. Such an arrangement is suitable for 100Base-T networks. Typically, the {circle around (3)}-{circle around (6)} and {circle around (4)}-{circle around (5)} pairs are constructed as straddled pairs which cause electrical problems. In order to meet the cross talk requirements, many designs for modular jack connectors address this problem by shifting or crossing over wires. In doing so, electrical performance for 1000Base-T will be severely and negatively affected. In addition, forcing the system to drive signals through the straddled pairs {circle around (3)}-{circle around (6)} and {circle around (4)}-{circle around (5)} will have detrimental effects on the data. Moreover, the {circle around (4)}-{circle around (5)} and {circle around (7)}-{circle around (8)} pairs that are not used in the jack are open circuited, thus increasing cross talk. As a result, the use of current standard Category 5 connectors actually degrades the system performance below Category 5 in the majority of cases.
As is well known in the art, present modular jack connectors comprise a rectangular housing defining a cavity therein, a dielectric insert retained within the cavity, a plurality of contacts molded into the insert, and a printed circuit board assembled vertically to a rear of the housing. One problem with the present modular jack connector is that a rearward end of each contact often terminates in a pin which inserts through a through hole defined in the printed circuit board and requires soldering therein, which is inconvenient to assemble.
Accordingly, what is desired is a modular jack connector, optimized for 1000Base-T, for use with presently existing copper wire cabling, which will allow Category 5 performance in these old copper wire communication networks. Such a modular jack connector meeting Category 5 performance standards and permitting easy and inexpensive assembling is also desired. When this modular jack connector is used in conjunction with the 1000BaseT protocol, a 4-fold improvement in data transmission is achieved over 100Base-T, thus extending the useful life of the copper network. This will call for a new wiring scheme in the modular jack on 1000Base-T systems and, finally, provide adequate electrical performance for system manufacturers to successfully promote this new standard to mainstream applications.
Accordingly, one objective of the present invention is to provide a modular jack connector that yields Category 5 performance in a copper wire network optimized for operation under the 1000Base-T protocol.
A second objective of the present invention is to provide a modular jack connector that yields Category 5 performance in a copper wire network, which is easy to assemble.
A third objective of the present invention is to provide a modular jack connector which yields Category 5 performance in a copper wire network, which is inexpensive to manufacture.
In order to achieve the objects set forth, a modular jack connector of the present invention comprises an insulative housing, an insert module received in the insulative housing, and a shield enclosing the insulative housing. The insert module includes an insert having an insulative body and a plurality of contacts retained in the insulative body, a printed circuit board vertically assembled to the rear of the insert, and a footer assembled to the rear of the printed circuit board and having a plurality of terminals retained therein.
The printed circuit board defines an upper array and a lower array of plated through holes interconnected with each other via conductive traces therebetween. The contacts of the insert include inclined mating portions for mating with corresponding contacts of a complementary plug connector, intermediate portions retained in the insulative body, and tail portions in the form of press-fit eyelet portions for being press fitted into the upper array of plated through holes of the printed circuit board. The terminals of the footer also include press-fit eyelet portions for being press fitted into the lower array of the printed circuit board. An electrical path is thus established within the insert module through the contacts of the insert, the plated through holes and conductive traces of the printed circuit board, and the terminals of the footer. Assembly and disassembly of the insert module are facilitated due to the provision of the press-fit eyelet portions of the contacts and the terminals of the respective insert and footer.
To yield Category 5 performance in a copper wire network optimized for 1000Base-T applications, the contacts of the insert are configured as 4 differential pairs all used for transmitting and receiving signals, wherein {circle around (1)}{circle around (2)} is a first pair for signal transmission, {circle around (3)}{circle around (4)} is a second pair for signal transmission, {circle around (5)}{circle around (6)} is a third pair for signal reception and {circle around (7)}{circle around (8)} is a fourth pair for signal reception. The intermediate portions of the contacts are arranged on two levels, wherein those of the {circle around (3)}{circle around (4)} and {circle around (7)}{circle around (8)} pairs are arranged on an upper level and those of the {circle around (1)}{circle around (2)} and {circle around (5)}{circle around (6)} pairs are arranged on a lower level. To reduce the cross talk induced between the contacts during engagement with the complementary plug connector, the distance between the intermediate portions of each pair is minimized and the distance between adjacent pairs on the same level is maximized. The printed circuit board, which functions as a cross talk compensating circuit board, also aids in meeting the 1000Base-T specifications by adding inter-digital compensation therein.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.